Device for grinding straight edges on planer cutter blades



M 1944- v H. E. SJGSTRAND 2,347,800

- DEVICE FOR GRINDING STRAIGHT EDGES ON PLANER CUTTER BLADES Filed Aug. 25, 1941 18 7 IQ I 17 30 9 20 f Y v 5 Patented May 2, 1944 DEVICE FOR GRINDING STRAIGHT EDGES ON PLAN ER CUTTER BLADES I-Ijalmar Emanuel Sjiistrand, Stockholm, Sweden Application August 25, 1941, Serial No. 408,276 In Sweden July 12, 1939 2 Claims.

My invention more particularly relates to a device for grinding straight edges on planer cutter blades while the same are still secured to the cutter head in the planer. The invention is substantially characterized by a support or standard, adapted to be attached to the planer table, and an arm carrying the grinder and a motor pivotably attached to said support. The device may also have an auxiliary standard to which the motor with the grinder is movably connected by means of a second pivotable arm.

My invention will best be understood by reference to the accompanying drawing, in which- Fig. 1 is a side elevation of an embodiment of the device as applied to a smoothing-planer, the latter being partly broken away;

Fig. 2 is a plan View of the same embodiment; and

Fig. 3 diagrammatically shows another embodiment of the invention, in which an auxiliary standard is used for guiding purpose, in order to obtain a straight line movement of the grinder.

In Figs. 1 and 2 reference character I denotes the grinder, which is of cup shape, and 2 the blade that is being ground secured to the cutter 3. The grinder I with hub and flange 4 is attached direct to the shaft of the motor 5, the latter being secured by means of screws 6 to a plate I on an arm 8. At its other end said arm 8 is provided with a cylindrical crosspiece 9, which is bored so as to slide on the turned standard II). The faced base I I of the standard is placed on the planed top of the planer table Ila. The cylindrical cross piece 9 has a slot I4 and a hand screw I so that the same may be adjusted to fit on the standard ID without any play.

The arm 8 is provided with lugs I6, which are bored and threaded to receive an adjusting screw I I, the upper end of which carries a crank-handle I8, while its lower end is provided with a glideshoe I9. A hand screw 20 with an intermediate thimble of fibrous material insures steadiness and friction to the adjusting screw II. A graduated scale 2| (partially broken away on the drawing) and an index finger 22 secured to the screw II facilitate the adjustment while grindin so that two or more cutter blades may be ground to the same height. The graduated scale 2I is provided with a circular guide member 23, fitting into a boring in the standard I0, and is further kept in its position by means of a sleeve 24 on the adjusting screw II. However, the grinder may also be adjusted in other ways, for example by means of the vertically adjustable table [2a.

In operation the tables I2a and I2!) are lowered to such level that the grinder will be clear of the same. The cutter is locked by means of a suitable stop screw. The grinder is lowered towards the blade by means of the adjusting screw I1 and moved forth and back over the blade by means of the handle 30. When the blade 2 is ground, the graduated scale 2I is read off, and the opposite blade is then ground to the same height.

When grinding the edges of such cutters as are mounted in a removable box, the latter is preferably placed with its upper planed face turned downwards on a plane table or plate, the cutter is locked and the grinding takes place as already described. It is suitable to place the box on parallel pieces so that the cutter can be turned without touching the plane table.

Instead of being driven by the motor 5 the grinder, of course, may also be driven by a belt, rope or another suitable transmission.

In the embodiment diagrammatically shown in Fig. 3 reference character It!) indicates an auxiliary standard, and 5a a motor without base and having two lugs 3|, which by means of pins 32 are turnably connected to the outer ends of the arms 8a and 8b which are pivotable around the standards. The grinder is fixed to the motor shaft as in Fig. l, and adjusting screws I'Ia and I Ib carry the same at the desired level. The standards Illa and Illb are placed on the iron table I2 in such a manner that the central lines o and c of the arms are parallel to one another and form right angles with the transverse line it when the arms and the motor 50. assume the middle position. In order that the sideward motion of the motor shaft shall be practically straight the pins 32 at middle position should have passed the line at as much as they are removed from said line in the outer positions. The dotted lines show the device in one of the outer positions. In the shown embodiment the arms 8a and 8b are symmetrical.

Obviously the embodiments and parts herein may be more or less varied from the exact constructions shown and described without departing from the spirit of the invention, and any means equivalent to said parts respectively may be employed, the essential novelty being in an attachment which may be mounted upon the planer bed or the like and support and operate a grinder after the manner and with the efiect obtained in and by the present device.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A device for grinding straight edges comcutter blades While the same are still secured to 10 the cutter head in the planer, having a standard, adapted to be attached to the planer table, a single rigid arm carrying and horizontally guiding the grinder and a motor, said arm being pivoted about an axis coinciding with the axis of the standard, and an auxiliary standard turnably connected to the motor and the grinder by means of a second pivotable arm.

HJALMAR EMANUEL SJ-GSTRAND. 

